Direct synthesis of unsolvated aluminum hydride involving Lewis and Bronsted acids

Unsolvated aluminum hydride has been synthesized by the direct reaction of aluminum bromide or sulfuric acid with an alkali metal tetrahydroaluminate at 90-102 degrees C in pure toluene or in toluene containing 5-10 wt % diethyl ether. The reaction involving aluminum bromide yields a mixture of unsolvated aluminum hydride phases of poor quality. The reaction with sulfuric acid affords a single-phase product as alpha-AlH3 at <= 90 degrees C.